This case report investigates the concurrent presence of post-traumatic stress disorder (PTSD) and bipolar disorder (BD) in the transgender population. We present a case involving a 21-year-old female-to-male transgender individual (preferred pronouns -they/them). The patient had a history of psychosis, trauma, gender dysphoria (GD), inconsistent hormone (testosterone) treatments, and a self-attributed diagnosis of "associative identity disorder" with 21 distinct "identities." They had two emergency admissions in quick succession, both characterized by analogous symptoms. Contributing factors included a recent discontinuation of antipsychotic medications and a history of cannabis use. Their family history included BD in the patient's mother and schizophrenia in their paternal grandfather. The differential diagnoses considered were brief psychosis, BD, PTSD, and substance-induced mania/psychosis. A notable improvement in the patient's clinical presentation was observed during their hospital stay. Their therapeutic regimen comprised olanzapine, hydroxyzine, topiramate, trazodone, and lithium carbonate extendedrelease. Additionally, the patient underwent psychological testing. This progress solidified the primary diagnosis as PTSD coexisting with BD, manifesting episodes of mania and psychosis. This report highlights the critical role of psychological evaluations in assessing symptoms in patients with multiple psychiatric comorbidities. Our findings emphasize the importance of a comprehensive, multidisciplinary approach for accurate diagnosis and efficacious treatment of such intricate cases.